This invention relates to transport or conveyor systems, and particularly to methods and means for merging vehicles travelling in two separate lanes into a single lane.
As used herein, the term "vehicle" is meant in the general sense to include any object whose movement is controlled within a transport or conveyor system.
Any traffic or transportation system with branching roads operating with freely moving objects, for example, street traffic, poses the problem of smoothly merging traffic at merge points, without excessive delays or stops. The problem is especially difficult where individual vehicles are to be fed from one traffic lane into a main traffic artery.
The aforementioned copending Application Ser. No. 234,605 discloses merger of two equidirectional single-lane traffic flows by forming gaps between the vehicles of each traffic flow even before a merge point is noticed, and then feeding the vehicles of one lane into the gaps of the other at the merge point. In a range before the merge point, the vehicles of the two traffic flows behave as if each of the lanes or tracks were already occupied with all the vehicles moving within this range on both tracks/lanes. Within each of the traffic flows, the speeds are first adjusted to each other. Vehicles of each traffic flow are signaled or imaged into the other flow and the signaled vehicle is "seen" by the adjacent object in the other traffic flow as an object immediately ahead of it. Furthermore, the traveling speed of each object is controlled in dependence on the traveling speed of the signaled object immediately ahead.
This system allows individual vehicles to pass through the merge point without stopping. When the speed of all the vehicles in the range ahead of the merge point is adjusted to the speed of the vehicle after the merge point, the two traffic flows before the merge point can practically never jam. However, it was found that, particularly in sections with a dense sequence of branches, the above mentioned adjustment of the speeds of the two traffic flows before the merge point can reduce the mean speed of the faster vehicles. This occurs when two vehicles following each other in separate lanes or tracks approach a merge point at different speeds. If the leading vehicle is the one whose speed is already adjusted to a nominal speed, and the following vehicle in the other lane is the faster vehicle, the latter is decelerated to the nominal speed when it reaches the above-mentioned range. That is, the faster vehicle is decelerated to the speed of the leading vehicle even though it has not received a signal from this (slower) vehicle.
An object of the invention is to improve systems and methods of this type.
Another object of the invention is to prevent the aforementioned difficulties.